Margrethe 1387 - 1412
Born 1353 at Söborg, Denmark. Parents: King Valdemar IV Atterdag of Denmark and Helvig of Sönderjylland.
Ruled Denmark from 1376 and Norway from 1380 in the name of her son Oluf. Defeated Albrekt 24 of February 1389 and was recognized as Queen of Sweden (a title she had used since 1375). She later ruled in the name of Erik, who in 1389 had been elected King of Norway and in 1396 King of Denmark and Sweden. She died 28 of October 1412 onboard her ship in the port of Flensborg.
Married 9 of April 1363 at Copenhagen's Palace to King Håkon VI of Norway. Child: Oluf.http://www.warholm.nu/Kongedahttp://en.wikipedia.org/wiki/Margrethe_Ihttp://da.wikipedia.org/wiki/Margrethe_I

This just reminds me of the TV show "Salve". It was about Sweden (or more correctly, the city of Kalmar) in 1397. (The show was made in 1997, so it took place six hundred years before that.) Eric of Pomerania and Queen Margarete were two very important characters in this show.

Thanks for your answers, also for the extra information
Well, I can imagine as well, that there were Queen consorts who had influence on the politics. But it's some kind of sad, that there weren't any other ruling Queens. It's always the men. Hopefully the future will be fairer.
That sentence used in Sweden is good.